docs: def _imul(self, n):
          """Concatenate n copies of self in place. Return self."""
          assert n >= 0
          if not n:
              self._clear()
              return self
          m = 1
          old_len = self.len
          while m * 2 < n:
              self._append(self)
              m *= 2
          self._append(self[0:(n - m) * old_len])
          return self